DE112021002077T5 - Electric braking device and electric braking control device - Google Patents

Abstract

A parking brake control device is provided that is configured, upon releasing a holding operation of a braking force, to energize an electric motor and to change a drive time of the electric motor in accordance with an amount of current change at a predetermined interval after a predetermined time has elapsed since a current value of the electric motor starts to decrease after an increase, and a current value at which the current change amount of the electric motor converges to a predetermined value or less.

Description

TECHNICAL AREA

This disclosure relates to an electric brake device and an electric brake control device that apply braking force to a vehicle, such as an automobile.

STATE OF THE ART

As a braking device mounted on a vehicle such as an automobile, there is known an electric braking device that rotates a braking member (e.g., a brake pad) against a braked member (e.g., a disk rotor) by driving (rotating) a motor (electric motor). presses when the vehicle is stopped or parked, for example, and holds a braking force. A disk brake device of Patent Literature 1 detects, when holding of the braking force is released, that the braking force has been released based on a derived value of a motor current, and stops driving the electric motor in a state where there is play between the brake pads and the disk rotors is secured based on the subsequent engine rotation amount.

CITATION LIST

PATENT LITERATURE

PTL 1: JP 2013-209041 A ( JP 6017162 B2 )

SUMMARY OF THE INVENTION

TECHNICAL PROBLEM

In the technique disclosed in Patent Literature 1, the distance between the brake member and the braked member may change when the hold of the braking force is released.

It is an object of one embodiment of the present invention to provide an electric brake device and an electric brake control device capable of securing backlash between a brake member and a braked member accurately when holding of braking force is released.

THE SOLUTION OF THE PROBLEM

According to an embodiment of the present invention, there is provided an electric brake device including: a motor configured to drive an electric mechanism configured to hold braking force by pressing a braking member against a braked member; and a controller configured to control driving of the motor, wherein the controller is configured to energize the motor upon releasing the holding of the braking force and to change a driving time of the motor in accordance with a current change amount at a predetermined interval, after a predetermined time has elapsed since a current value of the motor starts decreasing after rising, and a current value at which the current change amount of the motor converges to a predetermined value or less.

Furthermore, according to an embodiment of the present invention, there is provided an electric brake device including: a motor configured to drive an electric mechanism configured to hold a braking force by pressing a braking member against a braked member; and a controller configured to control driving of the motor, wherein the controller is configured to energize the motor and change a driving time of the motor based on a current value generated in each predetermined cycle when releasing the holding of the braking force is detected after the current value of the motor increases and then decreases to enter a predetermined current value range and a current value at which the current value becomes substantially constant.

Furthermore, according to an embodiment of the present invention, there is provided an electric brake control device for controlling a motor configured, an electric mechanism drive configured to hold a braking force by pressing a braking element against a braked element, wherein the electric brake control device is configured, when releasing the holding of the braking force, the electric brake control device is configured, when releasing the holding of the braking force, the motor with power to supply and change a driving time of the motor in accordance with a current change amount at a predetermined interval after a predetermined time has elapsed since a current value of the motor starts decreasing after rising, and a current value at which the current change amount of the motor falls to a predetermined value or less converged.

According to the one embodiment of the present invention, a clearance between the brake member and the braked member can be secured accurately when the hold of the braking force is released.

character list

• 1 12 is a conceptual diagram of a vehicle on which an electric brake device and an electric brake control device according to an embodiment of the present invention are mounted.
• 2 FIG. 14 is an enlarged vertical cross-sectional view of a disc brake with an electric parking brake function mounted on a rear wheel side of FIG 1 is arranged.
• 3 FIG. 12 is a block diagram showing a parking brake control device 1 along with a rear disc brake and other parts.
• 4 FIG. 14 is a flowchart showing the release control performed by the parking brake controller of FIG 1 is carried out.
• 5 FIG. 14 is a flowchart showing the processing of the judgment of step S5 of FIG 4 whether a current value is continuously within a no-load current range or not.
• 6 14 is a flowchart showing the processing of judging an no-load current value (freewheeling current value).
• 7 Fig. 12 is a flowchart showing the processing of a correction time calculation.
• 8th Fig. 12 is a characteristic diagram showing an example of the change over time of a current value of an electric motor.
• 9 Fig. 12 is an explanatory diagram showing the example of a time change of the current value of the electric motor together with the corresponding control processing (step numbers).
• 10 14 is an explanatory diagram showing an example of the change with time of the current value of the electric motor together with the correction time calculation processing.
• 11 14 is an explanatory diagram showing an example of the change with time in the current value of the electric motor when the temperature is low and the rotation resistance is large (when the freewheeling current value is large).
• 12 12 is an explanatory diagram showing an example of the change with time of the current value of the electric motor at high temperature and small rotation resistance (when the freewheeling current value is low).
• 13 14 is an explanatory diagram showing the processing of determining a driving time of the electric motor based on current values detected by a filter with a large time constant and a filter with a small time constant.
• 14 Fig. 14 is an explanatory diagram showing an error in filter delay and an error in motor rotation amount.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

An example of a case where an electric brake device and an electric brake control device according to an embodiment of the present invention are mounted on a four-wheel motor vehicle will now be described with reference to the accompanying drawings. in the in 4 until 7 In the flowcharts shown, each step is identified by using the notation "S" (e.g. step 1 = "S1").

1 until 13 are diagrams for illustrating the embodiment of the present invention. In 1 For example, a total of four wheels including, for example, front left and right wheels 2 (FL, FR) and rear left and right wheels 3 (RL, RR) are arranged on an underside (roadway side) of a vehicle body 1 constituting a vehicle body. The wheels (respectively the front wheels 2 and the rear wheels 3) together with the vehicle body 1 constitute the vehicle. The vehicle is equipped with a braking system for applying a braking force. The vehicle braking system will now be described.

On each of the front wheels 2 and the rear wheels 3, a disk rotor 4 is arranged as a braked member (rotating member) rotating together with each wheel (each front wheel 2 and each rear wheel 3). A braking force is applied to the disc rotor 4 for each front wheel 2 by a front wheel disc brake 5 which is a hydraulic disc brake. A braking force is applied to the disc rotor 4 for each rear wheel 3 by a rear wheel disc brake 6, which is a hydraulic disc brake with an electric parking brake function.

The pair (set) of rear wheel disc brakes 6 arranged corresponding to the left and right rear wheels 3 is a hydraulic pressure brake mechanism (hydraulic brake) that applies braking force by applying brake pads 6C (see 2 ) presses against the disc rotor 4 by hydraulic pressure. As in 2 1, the rear disc brakes 6 include, for example, a mounting member 6A called a carrier, a caliper 6B serving as a wheel cylinder, a pair of brake pads 6C serving as a braking member (friction member, friction lining), and a piston 6D serving as a pressing member. In this case, the caliper 6B and the piston 6D constitute a cylinder mechanism, that is, a cylinder mechanism in which the piston 6D is moved by hydraulic pressure to press the pads 6C against the disk rotor 4. FIG.

The mounting member 6</b>A is fixed to a non-rotating part of the vehicle and arranged so as to straddle an outer peripheral side of the disk rotor 4 . The caliper 6B is arranged on the mounting member 6A so that the disc rotor 4 can move in the axial direction. The caliper 6B includes a cylinder main body portion 6B1, a claw portion 6B2, and a bridge portion 6B3 connecting the cylinder main body portion 6B1 and the claw portion 6B2. A cylinder (cylinder hole) 6B4 is arranged in the cylinder body 6B 1 , and the piston 6D is fitted in the cylinder 6B4. The brake pads 6C are movably mounted on the mounting member 6A and arranged to be in contact with the disc rotor 4. As shown in FIG. The piston 6D presses the brake pads 6C against the disc rotor 4.

The caliper 6B drives the brake pads 6C through the piston 6D by feeding (adding) hydraulic pressure (brake hydraulic pressure) to the cylinder 6B4 based on operation of a brake pedal 9, for example. At this time, the pads 6C on both sides of the disc rotor 4 are pressed by the claw portion 6B2 of the caliper 6B and the piston 6D. As a result, a braking force is applied to the rear wheel 3 rotating together with the disc rotor 4. FIG.

The rear wheel disc brakes 6 further include an electric actuator 7 and a rotary-linear motion converting mechanism 8. The electric actuator 7 includes an electric motor 7A serving as a motor and a speed reducer (not shown) which slows down the rotation of the electric motor 7A. The electric motor 7A serves as a driving source for propelling the piston 6D. The rotation-linear motion converting mechanism 8 constitutes a holding mechanism (pressing member holding mechanism) that holds the pressing force of the brake pads 6C.

In this case, the rotation-linear motion converting mechanism 8 includes a rotation-linear motion element 8A which converts the rotation of the electric motor 7A into an axial displacement (linear displacement) of the piston 6D and drives the piston 6D. The rotary-linear moving member 8A consists of, for example, a screw member 8A1 composed of a bar-shaped body on which a male screw is formed, and a linear moving member 8A2 serving as a driving member and having a female screw hole formed on an inner peripheral side. The rotation-linear motion converting mechanism 8 converts the rotation of the electric motor 7A into displacement of the piston 6D in the axial direction, and holds the piston 6D driven by the electric motor 7A. That is, the rotation-linear motion converting mechanism 8 pushes the piston 6D through the electric motor 7A, drives the brake pads 6C by the piston 6D to press the pads 6C against the disk rotor 4, and holds the thrust of the piston 6D.

The rotation-linear motion converting mechanism 8 constitutes an electric mechanism of the electric brake device (electric parking brake device) together with the electric motor 7A. The electric mechanism converts the rotary force of the electric motor 7A into a thrust force via the reduction gear and the rotation-linear motion conversion mechanism 8 and drives (displaces) the piston 6D to press the brake pads 6C against the disk rotors 4 and the braking force of the vehicle hold. The electric motor 7A drives the electric mechanism. Such an electric mechanism (i.e., the electric motor 7A and the rotation-linear motion converting mechanism 8) constitutes the electric brake device together with a parking brake control device 24 described later.

The rear disc brakes 6 drive the piston 6D by the braking hydraulic pressure generated due to an operation of the brake pedal 9, thereby applying braking force to the wheels (rear wheels 3) and thereby to the vehicle by pressing the disc rotor 4 with the brake pads 6C. In addition, as described later, the rear disc brakes 6 apply a braking force (parking brake or auxiliary brake during travel, as required) to the vehicle by causing the electric motor 7A to rotate the piston 6D via the rotational-linear motion-to-linear motion converting mechanism 8 Response to an operation request based, for example, on a signal from a parking brake switch 23 to drive.

That is, the rear wheel disc brakes 6 drives the electric motor 7A and presses and holds the brake pads 6C against the disc rotor 4 by driving the piston 6D through the rotary-linear moving member 8A. In this case, the rear disc brakes 6 hold the braking of the vehicle by driving the piston 6D by the electric motor 7A in response to a parking brake request signal (request signal) which is a request for applying the parking brake. In addition, the rear disc brakes 6 brake the vehicle by supplying hydraulic pressure from a hydraulic pressure source (master cylinder 12, which will be described later, and a hydraulic pressure supply device 16 if necessary) in response to an operation of the brake pedal 9.

As described above, the rear disc brakes 6 include the rotation-linear motion conversion mechanism 8, which presses the brake pads 6C against the disc rotor 4 by the electric motor 7A and holds the pressing force of the brake pads 6C and can press the brake pads 6C against the disc rotor 4 by hydraulic pressure, which is added separately from the pressure applied by the electric motor 7A.

Meanwhile, the pair (set) of front wheel side disc brakes 5 arranged corresponding to the left and right front wheels 2 is configured in substantially the same manner as the rear wheel disc brakes 6 except for the mechanism related to the operation of the parking brake. That is, as in 1 1, the front disc brakes 5 include, for example, a fastener (not shown), a caliper 5A, brake pads (not shown), and a piston 5B, but not, for example, the electric actuator 7 (electric motor 7A) and the rotation-linear motion converting mechanism 8 for actuating and Release the parking brake. However, the front disc brakes 5 are identical to the rear disc brakes 6 in the point that the front disc brakes 5 drive the piston 5B by hydraulic pressure generated due to, for example, operation of the brake pedal 9 to thereby apply braking force to the wheels (front wheels 2) and therewith exert on the vehicle. That is, the front-wheel-side disc brakes 5 are a hydraulic brake mechanism (hydraulic brake) that applies braking force by pressing the brake pads against the disc rotor 4 by hydraulic pressure.

The front wheel disc brakes 5, like the rear wheel disc brakes 6, can be a disc brake with an electric parking brake function. Further, in this embodiment, the hydraulic disc brakes 6 including the electric motor 7A are used as the electric brake mechanism (electric parking brake). However, the electric brake mechanism is not limited to this, and for example, electric drum brakes that apply braking force by pressing a shoe against a drum by an electric motor, disc brakes that include a drum electric parking brake, and a cable-type electric parking brake that are applied by applying a parking brake working by pulling a cable by an electric motor can be used. That is, as the electric brake mechanism can use different types of electric brake mechanisms can be used as long as the electric brake mechanism can push (propel) a friction member (lining, shoe) against a rotating member (rotor, drum) based on driving an electric motor (electric actuator) and hold and release the pushing force.

The brake pedal 9 is arranged on a front tailgate side of the vehicle body 1 . The brake pedal 9 is actuated by the operator stepping on the pedal during a braking process of the vehicle. Depending on the operation of the brake pedal 9, a braking force is applied to and released from each of the disc brakes 5 and 6 as a regular brake (service brake). The brake pedal 9 includes a stop lamp switch, a pedal switch (brake switch), and a brake operation detection sensor (brake sensor) 10 such as a pedal stroke sensor.

The brake operation detection sensor 10 detects the presence or absence of operation of the brake pedal 9 and the operation amount, and outputs a corresponding detection signal to an ESC controller 17 . The detection signal of the brake operation detection sensor 10 is transmitted (is output to the parking brake control device 24) via a vehicle data bus 20 or a communication line (not shown) connecting the ESC control device 17 and the parking brake control device 24 .

The operation of the brake pedal 9 is transmitted through a brake booster 11 to the master cylinder 12 functioning as a hydraulic source (hydraulic pressure source). The booster 11 is configured as a negative pressure booster (atmospheric pressure booster) or an electric booster arranged between the brake pedal 9 and the master cylinder 12 . The booster 11 boosts the stepping force and transmits the boosted stepping force to the master cylinder 12 when the brake pedal 9 is depressed. At this time, the master cylinder 12 generates hydraulic pressure using brake fluid supplied (replenished) from a master reservoir 13 . The main tank 13 serves as an operating fluid tank in which the brake fluid is stored. The mechanism for generating the hydraulic pressure by the brake pedal 9 is not limited to the configuration described above, and may be a mechanism for generating the hydraulic pressure in response to the operation of the brake pedal 9, such as a brake-by-wire type mechanism.

The hydraulic pressure generated in the master cylinder 12 is supplied to a hydraulic pressure supply device 16 (hereinafter referred to as “ESC 16”) via a pair of cylinder-side hydraulic pressure lines 14A and 14B, for example. The hydraulic pressure supplied to the ESC 16 is supplied to the disc brakes 5 and 6 via brake-side pipe sections 15A, 15B, 15C and 15D. The ESC 16 is arranged between the disc brakes 5 and 6 and the master cylinder 12 . The ESC 16 is a hydraulic pressure control device that controls the hydraulic pressure of the hydraulic brakes (front disc brakes 5 and rear disc brakes 6). To this end, the ESC 16 contains a variety of control valves, a hydraulic pump that pressurizes the hydraulic pressure of the brakes, an electric motor that drives the hydraulic pump, and a hydraulic pressure control reservoir that temporarily stores excess brake fluid (neither of these items are shown). Each control valve and the electric motor of the ESC 16 are connected to the ESC controller 17, and the ESC 16 includes the ESC controller 17.

The opening and closing of each control valve of the ESC 16 and the driving of the electric motor are controlled by the ESC controller 17 . That is, the ESC control device 17 is an ESC control unit (ESC ECU) that controls the ESC 16 . The ESC control device 17 includes a microcomputer. The microcomputer controls and regulates electrically (the solenoid of each control valve and the electric motor) the regulator 16. In this case, the ESC controller 17 includes, for example, an arithmetic circuit that controls the hydraulic pressure supply to the ESC 16 and detects a malfunction of the ESC 16, and a drive circuit , which drives the electric motor and each control valve (neither of these parts are shown).

The ESC controller 17 individually controls and regulates each control valve of the ESC 16 and the electric motor for the hydraulic pump (the solenoid). As a result, the ESC controller 17 individually performs, for each of the disc brakes 5 and 6, the control of reducing, holding, boosting, or pressurizing the brake hydraulic pressure (wheel cylinder hydraulic pressure) supplied to each of the disc brakes 5 and 6 through the brake-side piping portions 15A to 15D becomes. In this case, the ESC controller 17 performs, for example, braking force distribution control, anti-lock brake control (hydraulic ABS control), vehicle stabilization control, hill start assist, traction control, vehicle following control, lane departure control, and obstacle avoidance control (automatic brake control and a brake control to avoid collision damage).

In normal operation based on a driver's brake operation, the ESC 16 directly supplies the hydraulic pressure generated by the master cylinder 12 to the disc brakes 5 and 6 (calipers 5A and 6B). Meanwhile, for example, when the anti-lock brake control is executed, the pressure increase control valve is closed to hold the hydraulic pressure of the disc brakes 5 and 6, and when the hydraulic pressure of the disc brakes 5 and 6 is reduced, the Pressure reduction control valve is opened and the hydraulic pressure of the disc brakes 5 and 6 is released to escape to the hydraulic pressure control reservoir. In order to perform stabilization control (skid prevention control) during driving when the hydraulic pressure supplied to the disc brakes 5 and 6 is increased or pressurized, the hydraulic pump is operated by the electric motor with the supply control valve in a closed state, and that by the hydraulic pump Discharged brake fluid is supplied to the disc brakes 5 and 6. At this time, on the suction side of the hydraulic pump, the brake fluid in the master reservoir 13 is supplied from the master cylinder 12 side.

Electric power from a battery 18 (or a generator to be driven by the engine), which is a power source of the vehicle, is supplied to the ESC controller 17 via a power supply line 19 . As in 1 shown, the ESC controller 17 is connected to the vehicle data bus 20 . It is also possible to use a well-known ABS unit instead of the ESC 16 . Further, it is also possible to directly connect the master cylinder 12 and the brake-side pipe sections 15A to 15D without arranging the ESC 16 (ie, omitting the ESC 16).

The vehicle data bus 20 forms a controller area network (CAN), which is attached to the vehicle body 1 as a serial communication unit. A large number of electronic devices mounted on the vehicle (e.g. various types of control devices including the ESC control device 17 and the parking brake control device 24) perform multiplex communication with each other in the vehicle via the vehicle data bus 20. In this case, the vehicle information transmitted to the vehicle data bus 20 is, for example, information (vehicle information) based on detection signals (output signals) from, for example, the brake operation detection sensor 10, an ignition switch, a seat belt sensor, a door lock sensor, a door opening sensor, a seat occupancy sensor, a vehicle speed sensor, a steering angle sensor, a Accelerator pedal sensor (accelerator pedal operation sensor), a throttle sensor, an engine speed sensor, a stereo camera, a millimeter-wave radar, a gradient sensor (tilt sensor), a gear shift sensor (transmission data), an acceleration sensor (G-sensor), a wheel speed sensor, and a tilt sensor that detects movement in a vehicle tilt direction . Other examples of the vehicle information transmitted to the vehicle data bus 20 include a detection signal from a W/C pressure sensor 21 that detects wheel cylinder pressure (W/C pressure) and a detection signal from an M/C pressure sensor 22 that detects master cylinder pressure ( M/C pressure) detected.

Next, the parking brake switch 23 and the parking brake control device 24 will be described.

A parking brake switch (PKB-SW) 23 serving as an electric parking brake switch is disposed in the vehicle body 1 at a position near the driver's seat (not shown). The parking brake switch 23 serves as an operation unit to be operated by the driver. The parking brake switch 23 transmits a signal (application request signal) corresponding to an application request of the parking brake (application request as a holding request or release request) to the parking brake controller 24 in response to an operation instruction from the driver. That is, the parking brake switch 23 outputs an operation request signal (operation request signal as a holding request signal or a release request signal) to the parking brake controller 24 to cause the piston 6D and hence the brake pads 6C to perform an operating operation (holding operation) or a releasing operation based on the drive (the rotation ) of the electric motor 7A. The parking brake control device 24 is a parking brake control unit (parking brake ECU).

When the parking brake switch 23 is operated to the braking side (application side) by the driver, that is, when there is an application request (brake hold request) for applying braking force to the vehicle, an application request signal (parking brake request signal or application command) is output from the parking brake switch 23. In this case, electric power is supplied to the electric motor 7A of the rear wheel disc brakes 6 via the parking brake controller 24 to rotate to the braking side. At this time, the rotation-linear motion converting mechanism 8 drives (pushes) the piston 6D toward the disc based on the rotation of the electric motor 7A benrotorseite 4 and holds the driven piston 6D. As a result, the rear wheel disc brakes 6 are in a state where a braking force is applied as a parking brake (or an auxiliary brake), that is, they are in an applied state (brake holding state).

Meanwhile, when the parking brake switch 23 is operated to the brake release side (release side) by the driver, i.e., when there is a release request (brake release request) for releasing the braking force of the vehicle, a release request signal (parking brake release request signal or release command) is output from the parking brake switch 23. In this case, electric power is supplied to the electric motor 7A of the rear wheel disc brakes 6 via the parking brake controller 24 to rotate in the direction opposite to the braking side. At this time, the rotation-linear motion converting mechanism 8 releases the holding of the piston 6D by the rotation of the electric motor 7A (releases the pressing force by the piston 6D). As a result, the rear wheel disc brakes 6 are in a state where the braking force as a parking brake (or auxiliary brake) is released, that is, they are in a released state (brake released state).

The parking brake control device 24 (electric brake control device) serving as the control device constitutes an electric brake device together with (the electric motor 7A and the rotation-linear motion converting mechanism 8) of the rear disc brakes 6. The parking brake controller 24 controls driving of the electric motor 7A. For this purpose, the parking brake control device 24, as shown in 3 1, a CPU 25 composed of, for example, a microcomputer, and a memory 26. Via the power supply line 19, the parking brake controller 24 is supplied with electric power from the battery 18 (or a generator driven by the engine).

The parking brake control device 24 controls driving of the electric motors 7A and 7A of the rear wheel disc brakes 6 and 6 and generates braking force (parking brake or auxiliary brake) when the vehicle is parked or stopped (and during travel as needed). That is, the parking brake controller 24 operates (applies and releases) the disc brakes 6 and 6 as parking brakes (auxiliary brakes as required) by driving the left and right electric motors 7A and 7A. For this purpose, an input side of the parking brake controller 24 is connected to the parking brake switch 23 and an output side of the parking brake controller 24 is connected to the electric motors 7A and 7A of the disc brakes 6 and 6. The parking brake controller 24 includes the arithmetic circuit 25 for, for example, detecting a driver's operation (operation of the parking brake switch 23), deciding whether or not to drive the electric motors 7A and 7A, and deciding whether to stop the electric motors 7A and 7A should or should not, and motor drive circuits 28 and 28 for controlling the electric motors 7A and 7A.

The parking brake controller 24 drives the left and right electric motors 7A and 7A based on, for example, an operation request (apply request or release request) generated by the driver operating the parking brake switch 23, an operation request based on an automatic application/auto-release judgment is based, or the like, and applies (holds) or releases the left and right disc brakes 6 and 6 . At this time, in the rear wheel disc brakes 6, the piston 6D and the pads 6C are held or released by the rotation-linear motion converting mechanism 8 based on the driving of each electric motor 7A. In this way, the parking brake controller 24 drives and controls the electric motor 7A to move the piston 6D (and hence the brake pads 6C) in response to the operation request signal for a holding operation (apply) or a release operation (release) of the piston 6D (and thus the brake pads 6C) to advance.

As in 3 shown, the arithmetic circuit 25 of the parking brake control device 24 is connected, in addition to the memory 26 serving as a storage device, for example to the parking brake switch 23, the vehicle data bus 20, a voltage sensor unit 27, the motor drive circuits 28 and current sensor units 29. From the vehicle data bus 20, various kinds of vehicle state quantities required for the control (actuation) of the parking brake, ie, various kinds of pieces of vehicle information can be obtained. Further, the parking brake controller 24 can output information and commands to various types of controllers including the ESC controller 17 via the vehicle data bus 20 or the communication line.

The vehicle information detected by the vehicle data bus 20 can also be obtained by directly connecting a sensor that detects the information to (the arithmetic circuit 25 of) the parking brake Sensing control device 24 are detected. Furthermore, the computing circuit 25 of the parking brake controller 24 may be configured such that an operation request based on the auto apply/auto release decision is input from another controller (e.g., the ESC controller 17) connected to the vehicle data bus 20 . In this case, the automatic application/auto release control may be performed by another controller such as the ESC controller 17 instead of the parking brake controller 24 . That is, it is possible to integrate the control content of the parking brake control device 24 into the ESC control device 17 .

The parking brake control device 24 includes the memory 26 serving as a storage device, which includes, for example, a flash memory, a ROM, a RAM or an EEPROM. The memory 26 stores processing programs used for parking brake control. The memory 26 stores, for example, processing programs for executing the in 4 until 7 processing flows shown and described later, that is, processing programs used for the control processing at the time of releasing the electric parking brake. In the embodiment, the parking brake control device 24 is separate from the ESC control device 17, but the parking brake control device 24 and the ESC control device 17 may be configured integrally (ie, integrated as a single brake control device). Further, the parking brake control device 24 controls two left and right rear wheel disc brakes 6 and 6 , but the parking brake control device 24 may be arranged for each of the left and right rear wheel disc brakes 6 and 6 . In this case, each parking brake control device 24 can be arranged integrally with the rear wheel disc brake 6 .

As in 3 1, the parking brake controller 24 includes, for example, the voltage sensor unit 27 that detects the voltage from the power supply line 19, the left and right motor drive circuits 28 and 28 that drive the left and right electric motors 7A and 7A, respectively, and the left and right current sensor units 29 and 29 29, which detect the motor current of the left and right electric motors 7A and 7A, respectively. The voltage sensor unit 27, the motor drive circuits 28 and the current sensor units 29 are connected to the arithmetic circuit 25, respectively. Consequently, in the arithmetic circuit 25 of the parking brake control device 24, when the parking brake is applied or released, for example, the decision (decision on completion of application and decision on completion of release) on stopping the drive of the electric motor 7A can be made on the basis of the of current value of the electric motor 7A detected by the current sensor units 29 (a change thereof). In the illustrated example, the voltage sensor unit 27 is configured to detect (measure) the power supply voltage, but the voltage sensor unit (voltage sensor) may be configured to measure the voltage between the terminals of the electric motors 7A and 7A and 7A independently for the left and right sides, for example 7A measures.

It is preferable that the electric parking brake can timely stop the electric motor 7A, which is an actuator, without using a position sensor or an axial force sensor. A case where the electric parking brake is released will now be considered. For example, in a case where the timing to stop the electric motor 7A is early when the electric parking brake is released from an application state, the return amount of the linear moving members 8A2, which is a driving member, is insufficient, and a backlash amount between the brake pads 6C and the disc rotors 4 may be insufficient. As a result, the rotational resistance of the disk rotors 4 may increase. When the timing for stopping the electric motor 7A is late, the return amount of the linear moving elements 8A2 becomes excessive (too large), and the time until the thrust is generated in the next application operation may be too long. That is, responsiveness at the time of application may decrease.

To suppress such a problem, for example, as in 14 shown by judging that the thrust (braking force) has been released based on the current and voltage curves of the electric motor, and by adjusting the control amount (motor speed) of the electric motor accordingly, thereafter the displacement amount (return amount) of the driving member and moreover the Game amount to be secured. However, judging that the thrust has been released (in other words, judging that the brake pads have come off) requires the use of a filter with a large time constant to suppress the influence of noise and ripple. As a result, it may be difficult to save the game accurately due to a delay caused by the filter. When the electric motor is controlled using a motor rotation amount estimated from the current and voltage waveforms, it is necessary to determine a motor rotation amount threshold for stopping the electric motor, taking into account, for example, the change in the characteristics of the electric motor and the generated force at the time of release. Besides that There is a monitoring error in current and voltage during the calculation of each cycle, which can be increased by the required calculation time. Therefore, it is necessary to set a large threshold value for the motor speed amount for stopping the electric motor, and from this aspect as well, it may be difficult to accurately save the backlash.

More specifically, the disc brake device of Patent Literature 1 described above judges that the brake pads are disengaged based on whether or not a derived value of the motor current has settled to a constant value. However, the actual current curve shows ripples. In addition, the friction of the threaded portion of the rotational linear motion mechanism varies depending on the screw position, thereby changing the current. Because of these factors, it is considered difficult to accurately assess whether the plaque has come loose. In order to achieve accurate judgment, it is conceivable to use a filter that is not easily affected by the current. In this case, however, there may be a delay in current changes and it may be difficult to achieve accurate control. Furthermore, in the disc brake device of Patent Document 1, backlash is secured by the amount of motor rotation. In this case, the motor speed is calculated by integrating the number of revolutions calculated from the voltage and current. However, monitoring errors in current and voltage as well as errors due to motor constant and resistance can be integrated. As a result, as the motor speed increases, backlash variation increases, and there is a possibility that sufficient control accuracy of the electric motor cannot be obtained.

In contrast, in the embodiment, a disengaged state of the brake pads 6C is judged by a "width of the current of the electric motor 7A" calculated based on, for example, the ripple of the electric motor 7A, the change in the threaded portion of the rotation-linear motion converting mechanism 8, and the change in others Mechanisms is estimated to secure the game accurately, and the amount of tax after the disengagement is controlled by using "time", for which there are few error-causing factors. In this case, “time” which is a control quantity after disengagement is calculated based on “constant current value after disengagement of brake pads 6C” and “current value at which current enters the current width of judgment of disengagement state” corrected. As a result, the control accuracy can be improved compared to a case where the “amount of rotation” is used as the control variable after disengagement. In addition, the control accuracy can be improved compared to a case where the "time" is not corrected after the clutch is disengaged.

That is, as in 13 1, in the embodiment, the current of the electric motor 7A is detected by a filter with a large time constant and a filter with a small time constant. In 13 a current 51 of the electric motor 7A, which is detected by a filter with a small time constant, is indicated by a solid characteristic line, and a current 52 of the electric motor 7A, which is detected by a filter with a large time constant, is indicated by a broken characteristic line line displayed. In the embodiment, the point in time when the current 51 detected by the filter with a small time constant reaches a constant current width IB (threshold width IB within an idle current range described later) is set as a preliminary pad release (pad release recognized by the controller). scored. Further, a coasting current value (ie, a current value at which the electric motor 7A runs forward with zero thrust, namely, an idling current value ID described later) is detected from the slope of the current 52 detected by the filter having a large time constant.

Then, the release is considered to be complete when a time T3 (time Tc, described later) which is the sum of a "time T1 (time Tb, described later) from when the current 51 of the electric motor 7A, the is detected by the filter with a small time constant, enters the range of the constant current width IB until the current reaches the value of the idle current (idle current value ID)", and a "time T2 (time Ta, described later) required to secure a clearance” elapses, and the electric motor 7A is stopped. The time T1 corresponds to a counter value C1 and the time T2 corresponds to a counter value C2. When the counter value reaches a value resulting from the addition of C1 and C2, the electric motor 7A is stopped. As a result, the influence of noise such as ripple generated in the current waveform at the time of release can be reduced, and the release can be secured accurately.

Therefore, in the embodiment as in FIG 4 until 12 , when the parking brake controller 24 releases the holding of the braking force, the parking brake controller 24 energizes the electric motor 7A and a drive time (time Tc, described later) of the electric motor 7A in accordance with one Amount of current change changes at a predetermined interval (interval of time Tb, described later) after a predetermined time has elapsed since the current value of the electric motor 7A starts decreasing after rising and the current value at which the amount of current change of the electric motor 7A becomes a predetermined value (threshold value Df, described later) or less converged. In this case, the predetermined time may be set as the time when an inrush current converges, for example. That is, at the time of release when the inrush current converges, the parking brake controller 24 changes the driving time (time Tc) of the electric motor 7A in accordance with the "current change amount of the electric motor 7A in the predetermined interval (interval of time Tb)" and the "current value As described later, the predetermined interval (time interval Tb) changes in accordance with a variation width of the current value depending on a temperature of the electric motor 7A . Further, the current value (idle current value ID) at which the current change amount of the electric motor 7A converges to the predetermined value (threshold value Df) or less is detected from the current waveform obtained through a differential filter.

In order to perform such control, the parking brake controller 24 includes a storage area for temporarily storing the current value at predetermined cycles. More specifically, the parking brake controller 24 includes a ring buffer (ring memory) to sequentially store the current value of each control cycle in a buffer. The number of buffers of the ring buffer for storage is fixed in advance. For example, the ring buffer stores the current values sequentially from a first buffer (zeroth buffer in the array), and when the number of buffers used for storage is exceeded, i.e. when a current value is stored in the last buffer, the ring buffer returns to beginning (zeroth buffer in the array) and continues storing (overwriting and updating) while discarding the previously stored current values in order.

As a result, when the parking brake controller 24 releases the hold of the braking force, the parking brake controller 24 energizes the electric motor 7A and changes the drive time (time Tc) of the electric motor 7A based on a current value detected every predetermined cycle after the current value of the electric motor 7A increases and then decreases to enter the predetermined current value range (threshold width IB within the no-load current range) and the current value (no-load current value ID) at which the current value becomes substantially constant. That is, at the time of releasing, the parking brake controller 24 changes the driving time (time Tc) of the electric motor 7A based on the “current value detected every predetermined cycle after the current value enters the predetermined current value range (threshold width IB within the no-load current range)” and the "current value (idle current value ID) at which the current value detected in each predetermined cycle becomes substantially constant." As described later, the current value range (threshold value width IB within the no-load current range) changes in accordance with the variation width of the current value depending on the Temperature of the electric motor 7A. The current value (idle current value ID) at which the current value becomes substantially constant is a current value at which a change in a derivative value of the current value obtained by the differential filter becomes equal to or smaller than a predetermined value. The control of the release drive of the electric motor 7A by the parking brake control device 24, that is, the in 4 until 7 illustrated control processing will be described later in detail.

The brake system of the four-wheel motor vehicle in the present embodiment has the configuration described above, and the operation of this brake system will now be described next.

When the driver of the vehicle steps on the brake pedal 9 and operates it, the stepping force is transmitted to the master cylinder 12 via the brake booster 11, and the master cylinder 12 generates hydraulic braking pressure. The brake hydraulic pressure generated in the master cylinder 12 is supplied to each of the disc brakes 5 and 6 via the cylinder-side hydraulic pressure lines 14A and 14B, the ESC 16, and the brake-side pipe portions 15A, 15B, 15C, and 15D to apply a braking force to each of the left and right front wheels 2 and each of the left and right rear wheels 3 to exercise.

In this case, in each of the disc brakes 5 and 6, as the brake hydraulic pressure in the calipers 5A and 6B increases, the pistons 5B and 6D are slid toward the brake pads 6C, and the brake pads 6C are pressed against the disc rotors 4 and 4. As a result, a braking force based on the braking hydraulic pressure is applied. When the brake is released, the supply of brake hydraulic pressure to the calipers 5A and 6B is cut off, causing the pistons 5B and 6D to move away (retract) from the discs 4 and 4. As a result, the Brake pads 6C from discs 4 and 4, and the vehicle returns to a non-braking condition.

When the driver of the vehicle sets the parking brake switch 23 to the braking side (actuating side), the electric motor 7A of the left and right rear disc brakes 6 is energized by the parking brake controller 24 and rotated and driven. In the rear wheel disc brakes 6, the rotary motion of the electric motor 7A is converted into linear motion by the rotary-linear motion converting mechanism 8, and the piston 6D is driven by the rotary-linear motion member 8A. As a result, the disk rotor 4 is pressed by the brake pads 6C. At this time, the rotation-linear motion converting mechanism 8 (linear motion element 8A2) holds a braking state by a frictional force (holding force) generated by screw engagement, for example. As a result, the rear wheel disc brakes 6 are operated (applied) as a parking brake. That is, even after the power supply to the electric motor 7A is stopped, the piston 6D is held at the braking position by the rotation-to-linear conversion mechanism 8.

When the driver turns the parking brake switch 23 to the brake releasing side (release side), the electric motor 7A is energized from the parking brake controller 24 so that the motor is driven in reverse. By this power supply, the electric motor 7A is rotated in the opposite direction than when the parking brake is operated (applied). At this time, the holding of the braking force by the rotation-linear motion converting mechanism 8 is released, and the piston 6D can be displaced in the direction away from the disk rotor 4. This releases the rear wheel disc brakes 6 from operating as a parking brake.

Next, the control processing performed by the arithmetic circuit 25 of the parking brake controller 24 will be described with reference to FIG 4 until 7 described. The tax processing of 4 until 7 is repeatedly executed in a predetermined control cycle (eg, 10 ms) during the period in which the parking brake controller 24 is energized, for example. Furthermore, in 8th a relationship between the time change of the current value of the electric motor 7A and the driving time (judgment time Tc) of the electric motor 7A obtained by the control processing of FIG 4 until 7 is assessed. In 9 FIG. 12 is a relationship between the change over time in the current value of the electric motor 7A and each step of the control processing of FIG 4 until 7 shown. In 10 FIG. 12 is a relationship between the change over time in the current value of the electric motor 7A and the correction time calculation processing of FIG 7 shown. In the 8th until 10 the current values stored in the ring buffer are represented by circles on the characteristic (on the current 51) (the same applies to those described later 11 and 12 ).

When the parking brake control device 24, which is an electronic control unit (ECU), is activated, the control processing of 4 started. In step S1, the parking brake controller 24 judges whether or not a release operation has started. That is, when a release command based on the operation of the parking brake switch 23 to the release side or when a release command based on the release judgment logic of the parking brake is issued, the electric motor 7A is energized. As a result, the electric motor 7A is driven in a releasing direction. In step S1, it is judged based on the release command whether or not the electric motor 7A has started running.

If step S1 is judged as "NO", that is, if it is judged that the release has not started (driving of the electric motor 7A in the release direction has not started), the process returns to the start. That is, the process proceeds to the "end" of 4 advances, then returns to "Start" and the processing steps after step S1 are repeated. Meanwhile, when step S1 is judged as “YES”, that is, when it is judged that release has started, the process proceeds to step S2. In this case, ie when the step S1 of 4 is assessed as "YES", the processing of 5 until 7 started. The processing of 5 until 7 will be described later.

In step S2, the current signal of the electric motor 7A, which is detected by the current sensor unit 29, is filtered. That is, in step S2, filter processing for judging the no-load current is performed. The filter is set considering, for example, a duty cycle and a delay time. In the present embodiment, for example, a cut-off frequency is set to 50 Hz or less and a 90% response time to 10 ms or less of a control judgment cycle for a 1 ms signal. In addition, the filter can also be set to values other than these to improve responsiveness. In 8th until 10 is the filter processing of step S2 (and step S11 of 5 and step S31 of 7 ) obtained current 51 represented by a solid characteristic line.

In step S3 subsequent to step S2, it is judged whether or not a current mask time has elapsed from the start of the release. That is, in step S3, it is judged whether or not a sufficient time has elapsed for the inrush current generated immediately after the rotation of the electric motor 7A starts to converge. For example, this time (current mask time) may be a value where a margin in the sum of a “time from when the start of release is judged to a relay operation” and a “time during which the inrush current lasts “, is taken into account. The start of tripping can be judged based on the issuance of the trip command. If step S3 is judged "NO", i.e. if it is determined that the current mask time has not elapsed since the start of the release (issuance of the release command), the process returns to the beginning. Meanwhile, if step S3 is judged "YES", i.e., if it is judged that the current mask time has elapsed since the start of the release (issuance of the release command), the process proceeds to step S4.

In step S4, it is judged whether or not the current value of the electric motor 7A subjected to the filter processing in step S2 is equal to or smaller than an idling judgment current value IA. That is, in step S4, it is judged whether or not the current value has entered an idle state region after the mask time has elapsed since the release start. The no-load state corresponds to a state in which the pistons 6D have separated from the pads 6C, in other words, a state in which the linear motion elements 8A2 have separated from the pistons 6D. The no-load judgment current value IA, that is, the threshold value IA of the current used for judging whether the current is in an no-load state or not, can be set from an upper limit value in consideration of the current change in the no-load state. The factors of current variation are determined by considering all of the following factors, i.e., change in properties due to temperature, mechanical resistance of components, viscous resistance, and change in efficiency.

Specifically, the factors of current fluctuation are considered considering torque fluctuation due to sliding resistance of parts that rotate or move linearly such as screws, bearings and O-rings, torque fluctuation due to viscous resistance of grease, motor inductive resistance, torque constant, inertia and of motor resistance (harness resistance, coil resistance and resistance between terminals). In addition to these factors, the current value can also be calculated by adding factors that result in changes in torque and current in the no-load condition. The threshold value IA for judging idling is determined in advance, e.g. on the basis of calculation, experiment, test or simulation. If step S4 is judged "NO", i.e. if it is judged that the current value of the electric motor 7A is larger than the current value IA for idling judgment, the process returns to the start. Meanwhile, when step S4 is judged "YES", i.e. when it is judged that the current value of the electric motor 7A is equal to or smaller than the idling judgment current value IA, the process proceeds to step S5.

In step S5, it is judged whether or not the current value is continuously within the no-load current range. That is, in step S5, based on the processing of 5 judges whether or not the current value of the electric motor 7A is continuously within the predetermined current width IB (ie, within the threshold width IB within the no-load current range). The release time is generally about one second, and the temperature of the electric motor 7A during the release within this time can be considered to be almost constant. Therefore, the judgment is performed utilizing the fact that in the no-load current range in which all fluctuations have been taken into account, that is, in the range equal to or smaller than the no-load judgment current value IA, the no-load current fluctuation range is reduced by the smaller current width IB (IA>IB ) can be defined. The current width IB, which is the threshold width within the no-load current range, can be calculated by excluding the element of the temperature characteristic change from the above-mentioned fluctuating elements of the no-load judgment current value IA. In step S5, ie in the processing of 5 , it is judged whether or not the current value of the electric motor 7A is continuously within the threshold width IB within the no-load current range.

If the step S1 of 4 is judged as "YES", the processing of starts 5 (Process of judging whether or not the current value is continuously within the no-load current range). Step S 11 of 5 is the same processing step as step S2 of 4 , and step S12 of 5 is the same processing step as step S4 of 4 . If the step S12 of 5 judged as "NO", the process returns to the beginning. That is, the process proceeds to "End", then returns to "Start", and the processing steps after step S11 are repeated. If step S12 is judged as "YES", the process proceeds to step S13. In step S13, the current value is stored in the ring buffer. That is, in step S13, the current value is stored in the ring buffer every cycle to judge whether or not the current value is continuously within the no-load current range. The required number of storages can be, for example, the sum of the maximum time Ta required to secure the play of the brake pads 6C and an estimated maximum time Tb until the current value after reaching the threshold width IB within the no-load current range to the no-load current value levels off, be.

The maximum time Ta can be set based on a “required backlash”, a “spindle lead”, a “reduction ratio”, and a “motor speed (slowest state)”. That is, the time Ta for securing the pad play is given by the following formula (1).

$${\text{T}}_{\text{a}}=\frac{\left(\frac{\text{required game}}{\text{pitch}}\right)\times \text{reduction ratio}\ddot{\text{a}}\text{ltnis}}{\text{engine speed}}$$

Here, Tb depends on the threshold width IB within the no-load current range and the slope of the deceleration (rigidity), and thus Tb can be calculated from the lowest conditions of the estimated caliper rigidity and pad rigidity. The calculation formula is the following formula (2).

$${\text{T}}_{\text{b}}=\frac{\text{rotation of the sliding screw}\left[\text{mm}\right]{\text{when changing from I}}_{\text{s}}}{\text{Sliding screw rotation speed}\left[\text{mm/s}\right]}$$

Formula (2) becomes the following formula (3).

$${\text{T}}_{\text{b}}=\frac{\left(\frac{\text{rigidity}\left[\text{mm/kn}\right]}{\text{torque}-\text{scrap}-\text{conversion coefficient}\left[\text{Nm/kg}\right]}\times \text{torque constant}\left[\text{Nm/a}\right]\right)\times I_s\left[A\right]}{\text{engine speed}\left[\text{rpm}\right]\text{/}60\text{/reduction ratio}\ddot{\text{a}}\text{ltnis}[-]\times \text{Game}\left[\text{mm/rev}\right]}$$

In step S13 following step S14, it is confirmed whether or not the change in current value is within the threshold width IB within the no-load current range based on the difference between the maximum and minimum current values stored in the ring buffer, and it is monitored whether the current value is in the idle state. That is, in step S14, it is judged whether the difference between the maximum and minimum ring buffer values from [0] to [Tc equivalent] is equal to or smaller than the threshold width IB within the no-load current range. Judgment is made after current values from [0] to [Tc equivalent] have accumulated in the ring buffer. Until then, the current values are stored in the ring buffer (process returns to step S13). Tc corresponds to the time (assessment time Tc) resulting from the addition of the time Ta for securing the base and the correction time Tb' described later (Tc=Ta+Tb' (maximum of Tb' is Tb' =Tb)) . If step S14 is judged "NO", i.e. if it is judged that the difference between the maximum and the minimum of the ring buffer values exceeds the threshold width IB within the no-load current range, the process returns to the previous step S13. Meanwhile, if step S14 is judged "YES", i.e. if the difference between the maximum and minimum of the ring buffer values is equal to or smaller than the threshold width IB within the no-load current range, the process proceeds to step S15.

When the sliding resistance of an O-ring or bearing changes due to hydraulic pressure generation and the current value exceeds the threshold width IB within the idling current range, step S14 is not satisfied and the processing steps of step S13 and step S14 continue. As a result of the processings of step S13 and step S14, it is judged that the idling current fluctuation range is within the threshold width IB within the idling current range in accordance with the position at which the actual idling current levels off within the no-load current range (within the range equal to or smaller than the no-load judgment current value IA).

In step S15, as in 8th shown, based on the judgment of step S14, that is, by judging that the idling state has continued at a certain temperature for the judging time Tc, it is judged that the judgment as to whether the current value is continuously within the idling current range or not is satisfied, and the process returns to the start. In this case, step S6 of 4 rated as "YES". The judgment time Tc is the sum of the above-mentioned time Ta and the correction time Tb' given by the in 6 differential judgment processing shown and the in 7 correction time calculation processing shown (Tc=Ta+Tb'). The correction time Tb ' is taken from the in 7 correction time calculation processing shown in FIG 6 shown differential judgment processing.

The differential judgment processing of 6 will now be described. If step S1 of 4 is judged as "YES", the processing of starts 6 (Differential judgment processing). In step S21, the filter processing for differential judgment is performed. That is, in step S21, in order to remove the influence of the ripple and noise, large time constant filter processing is performed. More specifically, in step S21, the current signal of the electric motor 7A is subjected to filter processing using a filter (differential filter) having a time constant larger than that in step S2 of FIG 5 , step S11 of 6 and step S31 of 7 , which will be described later. The correction time calculation must be completed before the pad spacing is saved. Therefore, for example, in step S21, the filter processing is performed so that a 90% response is achieved for a time obtained by subtracting a margin from the required number (required time) of the ring buffer described above. In 9 and 10 the current S2 obtained by the filter processing of step S21 is indicated by an alternate long and short dashed characteristic.

In step S22 subsequent to step S21, it is judged whether or not the current value of the electric motor 7A subjected to the filter processing in step S21 is equal to or smaller than the idling judgment current value IA. If step S22 is judged "NO", the process returns to the beginning. That is, the process proceeds to “End”, then returns to Step S21, and the processing steps after Step S21 are repeated. Meanwhile, when step S22 is judged as "YES", the process proceeds to step S23. In step S23, the current derivative value is calculated. Step S24 to Step S26 are steps for judging that the state in which the current derivative value is equal to or smaller than the threshold value Df continues for a certain time (predetermined time). The threshold Df of the current derivative value is a threshold for judging that the current is the no-load current value ID ( 10 ), and can be any value between a slope Db of the current when the thrust is decreasing most slowly and a derivative value Dc when the current has changed by an assumed current width at the time of idling (Dc<Df<Db). The slope of the current can be calculated considering, for example, the rigidity, a sliding resistance in rotation or linear movement, and the specifications of the motor. The specified time can be set as a time for appropriately judging that the current has converged to the no-load current value ID (time for judging that the derivative value has settled to Df or less).

In step S24, it is judged whether or not the current derivative value calculated in step S23 is equal to or smaller than the threshold value Df. If step S24 is judged "NO", i.e. if it is judged that the current derivative value exceeds the threshold value Df, the process returns to the start. When step S24 is judged "YES", i.e. when it is judged that the current derivative value is equal to or smaller than the threshold value Df, the process proceeds to step S25. In step S25, a counter is incremented, and in subsequent step S26, it is judged whether or not the counter has exceeded the predetermined time. If "NO" is determined in step S26, i.e. if it is determined that the counter is within the specified time, the process returns to the beginning. If YES in step S26, that is, if it is determined that the counter exceeds the predetermined time, the process proceeds to step S27. In step S27, the current value at the time when the process proceeds to step S27 is held as the idle current value ID. That is, in step S27, the current value at the time when the derived value settles to Df or less is held as the idle current value ID, and the process returns to the start.

Next, the processing of the correction time calculation of 7 described. In the correction time calculation processing, the time until the current value falls within the threshold width IB within the no-load current range is corrected based on the actual waveform. The aim of this processing is to calculate the time from the entry of the first current buffer value into the threshold width IB within the no-load current range to the entry of the current value into the no-load current value ID is calculated by the differential judgment mentioned above. Step S31 to Step S33 of 7 are the same processing steps as step S11 to step S13 of 4 . That is, in step S31, filter processing for judging the idle current is performed, and in step S32, it is determined that the current value has become a current value IA or less that can be determined as an idle state. If step S32 is judged "NO", the process returns to the beginning. That is, the process proceeds to "End", then returns to "Start", and the processing steps after step S31 are repeated. If step S32 judges "YES", the process proceeds to step S33. In step S33, the current value is stored in the ring buffer (the same buffer value as in the no-load current calculation is used). In step S34 subsequent to step S33, a comparison with an idle current equivalent value IE (also referred to as “idle current detection correction value IE”) is performed in order from the 0th array of the ring buffer.

That is, in step S34, it is judged whether or not the value of the ring buffer and the idle current equivalent value IE agree. As in 10 shown, the no-load current equivalent value IE is a current obtained by adding an amount of fluctuation (IC) due to the changes in sliding resistance in no-load state and the monitoring error to the no-load current value ID calculated by the above-mentioned differential judgment. The time constant of the filter in this processing (correction time calculation processing) is set lower than the time constant of the filter in the differential judgment, and therefore the no-load current equivalent value IE is set considering the influence of fluctuations. If step S34 is judged as "NO", that is, if it is judged that the value of the ring buffer does not match the idle current equivalent value IE, the process returns to the beginning. If step S34 is judged as "YES", that is, if it is judged that the value of the ring buffer agrees with the idle current equivalent value IE, the process proceeds to step S35. In step S35, the correction time is calculated from the ring buffer array (eg, N-th array) judged to match in step S34. As in 10 shown, the zeroth array is considered to be the point where the current value enters the threshold width IB within the no-load current range, and the Nth array (e.g. the third array) is considered to be the point where the no-load current is reached, and therefore, this interval becomes the time interval to be corrected. That is, the correction time Tb' can be expressed by the following formula (4) from the number of fields N and the task cycle (control cycle).

$$\text{Correction time Tb}\text{'}=\text{N}\times \text{control cycle}$$

For the correction time Tb', a standard time Toriginal can be set in advance and the difference from this value can be provided as feedback. In this case, when the correction time Tb' is longer than the standard time Toriginal (Tb'>Toriginal), the judgment time Tc is controlled for a longer time than the specified time. This is to deal with cases where the slope of the current curve gradually decreases due to the unexpected frictional resistance of the brake pads 6C. In any case, when the correction time Tb' has been calculated in step S35, the process returns to the beginning. The correction time Tb' calculated in step S35 is added to the anti-backlash time Ta and as the judgment time Tc in step S14 of 5 used (Tc=Ta+Tb').

In step S14 and step S15, when the difference between the maximum and minimum current values stored in the ring buffer from the time the current value enters the threshold width IB within the no-load current range until reaching the judgment time Tc becomes equal to or is smaller than the threshold width IB within the no-load current range judges that the judgment as to whether the current value is continuously within the no-load current range or not is satisfied. As a result, step S6 of 4 judged as "YES", and in step S7, the driving of the electric motor 7A is stopped. Also, in step S7, the ring buffer values are cleared and the process returns to the beginning. In this way, in step S6, the satisfaction of the judgment as to whether or not the current value is continuously within the no-load current range is made based on the judgment result of the processing of FIG 5 is judged, and when the judgment is satisfied, the driving of the electric motor 7A is stopped in step S7 and the release is completed.

In 11 1 shows an example of how the current value of the electric motor 7A changes with time when the temperature is low and the rotation resistance is large (when the freewheeling current is large). That means in 11 a characteristic curve is shown when, for example, the viscous resistance of the grease is large and the free-flowing current is high, for example, at a low temperature. In 12 1 shows an example of the change with time of the current value of the electric motor 7A when the temperature is high and the rotation resistance is small (when the freewheeling current is low). That means in 12 a characteristic curve is shown, when the viscous resistance of the grease is small and the flywheel current is low and/or the motor efficiency and engine efficiency are good and the flywheel current is low, such as at a high temperature. As in 11 and 12 1, the interval of Tb' corresponding to the predetermined interval changes in accordance with the variation width of the current value depending on the temperature of the electric motor 7A. The predetermined interval (Tb') becomes longer or shorter depending on the temperature. Further, within the no-load current range corresponding to the current value range, the threshold width IB changes according to the variation width of the current value depending on the temperature of the electric motor 7A. The current value range (width IB) moves parallel to the higher or lower current side depending on the temperature. In such an embodiment, the backlash can be accurately controlled by using the no-load current value ID used in the processing of 6 (differential judgement) was obtained and the correction time Tb' used in the processing of 7 (time judgment) was obtained, in the judgment time Tc included in the release processing of 4 and 5 is used must be taken into account. The white circles in 12 indicate that due to the number of buffers of the ring buffer used for storage being reached, the data has been discarded prior to the interval in which the current value is determined to be equal to or less than the threshold IA and fits within the width IB for Tc.

As described above, in the embodiment, when the parking brake is released, the electric motor 7A is stopped using the running time (judgment time Tc), which is the time for driving the electric motor 7A. In this case, the driving time (judgment time Tc) of the electric motor 7A is determined in accordance with the "current change amount in the predetermined interval (interval of Tb')" and the "current value (idle current value ID) at which the current change amount becomes a predetermined value (threshold value Df ) or less converged”. In other words, the driving time (judgment time Tc) of the electric motor 7A is determined in accordance with the “current value detected every predetermined cycle after the current value of the electric motor 7A has entered a predetermined current value range (threshold width IB within the no-load current range)” and changed to the “current value (idle current value ID) at which the current value becomes substantially constant”. Therefore, it is possible to more accurately judge the driving stop (release termination) of the electric motor 7A than in the case of using the motor rotation amount. Consequently, the game can be secured accurately, and fluctuations in the game can be suppressed. As a result, the response at the time of next application can be stabilized in a high range.

At the in 11 and 12 In the embodiment shown, the predetermined interval (interval of Tb') and the current value range (threshold value width IB within the no-load current range) change in accordance with the variation width of the current value depending on the temperature. Therefore, it is possible to save the game accurately regardless of the ambient temperature. Furthermore, in this embodiment, the no-load current value ID, that is, the current value at which the current change amount of the electric motor 7A converges to a predetermined value (threshold value Df) or less, is detected from a current waveform obtained by the differential filter. In other words, the no-load current value ID, which is the current value at which the current value is substantially constant, is a current value at which the change in the derivative value of the current value obtained by the differential filter is equal to or smaller than a predetermined value ( Threshold Df) is. Therefore, the idle current value ID can be accurately and stably detected by a differential filter having a large time constant. As a result, it is possible to stably judge the stopping of driving (completion of release) of the electric motor 7A by changing the driving time (judgment time Tc) using the current value after the filter.

In the embodiment, a case where the rear wheel disc brakes 6 are hydraulic disc brakes having an electric parking brake function and the front wheel disc brakes 5 are hydraulic disc brakes not having an electric parking brake function has been described as an example. However, the present invention is not limited to this. The rear wheel disc brakes 6 can be hydraulic disc brakes without an electric parking brake function, and the front wheel disc brakes 5 can be hydraulic disc brakes with an electric parking brake function. Further, both the front wheel disc brakes 5 and the rear wheel disc brakes 6 may be hydraulic disc brakes with an electric parking brake function. In short, the brakes of at least a pair of left and right wheels of the wheels of the vehicle can be configured as the electric parking brakes.

In the embodiment, as the electric braking mechanism, hydraulic disc brakes 6 with an electric parking brake have been described as an example. However, the brake mechanism is not limited to a disc brake type and can be configured to a drum brake type. In addition, various types of electric parking brake configurations can be adopted, for example, a drum-in-disc brake with a drum-type electric parking brake in the disc brake, and a configuration in which the parking brake is held by an electric motor by pulling a cable.

As the electric brake device based on the embodiment described above, for example, the aspects described below can be considered.

According to a first aspect, there is provided an electric brake device including: a motor configured to drive an electric mechanism configured to hold a braking force by pressing a braking member against a braked member; and a controller configured to control driving of the motor, wherein the controller is configured to energize the motor upon releasing the holding of the braking force and to change a driving time of the motor in accordance with a current change amount at a predetermined interval, after a predetermined time has elapsed since a current value of the motor starts decreasing after rising, and a current value at which the current change amount of the motor converges to a predetermined value or less.

According to this first aspect, when the hold of the braking force is released, the motor is stopped using the driving time, which is the time for driving the motor. In this case, the driving time of the motor is changed in accordance with the "current change amount in the predetermined interval" and the "current value at which the current change amount converges to the predetermined value or less". Therefore, it is possible to judge the driving stop (release termination) of the motor more accurately than in the case of using the motor rotation amount. As a result, backlash can be accurately secured, and response at the time of next use can be stabilized in a high range.

According to a second aspect of the first aspect, the predetermined interval changes in accordance with a variation width of the current value depending on a temperature of the motor. According to this second aspect, it is possible to accurately secure the game regardless of the ambient temperature.

According to a third aspect, in the first aspect or the second aspect, the current value at which the current change amount of the motor converges to the predetermined value or less is detected from a current waveform obtained through a differential filter. According to this third aspect, the current value at which the current change amount converges to the predetermined value or less can be detected accurately and stably by the differential filter. As a result, it is possible to stably judge the stopping of driving (completion of release) of the motor by changing the driving time using the current value after the filter.

According to a fourth aspect, there is provided an electric brake device including: a motor configured to drive an electric mechanism configured to hold braking force by pressing a braking member against a braked member; and a controller configured to control driving of the motor, wherein the controller is configured to energize the motor and change a driving time of the motor based on a current value generated in each predetermined cycle when releasing the holding of the braking force is detected after the current value of the motor increases and then decreases to enter a predetermined current value range, and a current value at which the current value becomes substantially constant.

According to this fourth aspect, when the hold of the braking force is released, the motor is stopped using the driving time, which is the time for driving the motor. In this case, the driving time of the motor is determined in accordance with the "current value detected every predetermined cycle after the current value of the motor has entered the predetermined current value range" and the "current value at which the current value becomes substantially constant". changed. Therefore, it is possible to judge the stop of driving (completion of release) of the motor more accurately than in the case of using the motor rotation amount. As a result, the game can be secured accurately, and the responsiveness at the time of next use can be stabilized in a high range.

According to a fifth aspect of the fourth aspect, the predetermined current value range changes in accordance with a variation width of the current value depending on a temperature of the engines. According to this fifth aspect, it is possible to accurately secure the game regardless of the ambient temperature.

According to a sixth aspect of the fourth aspect or the fifth aspect, the current value at which the current value becomes substantially constant is a current value at which a change in a derivative value of the current value obtained by a differential filter is equal to or smaller than a predetermined value becomes. According to this sixth aspect, the current value at which the current value becomes substantially constant can be obtained accurately and stably by the differential filter. As a result, it is possible to stably judge the stopping of driving (completion of release) of the motor by changing the driving time using the current value after the filter.

According to a seventh aspect, there is provided an electric brake control device for controlling a motor configured to drive an electric mechanism configured to hold a braking force by pressing a braking element against a braked element, the electric brake control device being configured when the holding of the braking force is released, the electric brake control device is configured, upon releasing the holding of the braking force, to energize the motor and to change a drive time of the motor in accordance with an amount of current change at a predetermined interval after a predetermined time has elapsed since a current value of the motor starts decreasing after rising, and a current value at which the current change amount of the motor converges to a predetermined value or less.

According to this seventh aspect, when the holding of the braking force is released, the motor is stopped by using the driving time, which is the time for driving the motor. In this case, the driving time of the motor is changed in accordance with the "current change amount in the predetermined interval" and the "current value at which the current change amount converges to the predetermined value or less". Therefore, it is possible to judge the driving stop (release termination) of the motor more accurately than in the case of using the motor rotation amount. As a result, the game can be secured accurately, and the responsiveness at the time of next use can be stabilized in a high range.

It should be noted that the present invention is not limited to the embodiment described above and includes other various modification examples. For example, in the embodiment described above, the configurations are described in detail in order to clearly describe the present invention, but the present invention is not necessarily limited to an embodiment including all the configurations that have been described. Furthermore, part of the configuration of a specific embodiment may be replaced with the configuration of another embodiment, and the configuration of another embodiment may also be added to the configuration of a specific embodiment. Further, another configuration may be added to or deleted from the configuration of each of the embodiments, or a part of the configuration of these embodiments may be replaced.

The present application claims priority based on Japanese Patent Application No. 2020-062317 , which was filed on March 31, 2020. All disclosed contents including specification, scope of claims, drawings and abstract of Japanese Patent Application No. 2020-062317 , filed March 31, 2020, are incorporated herein by reference in their entirety.

Reference List

4

disc rotor (braked element),

6

rear disc brake,

6C

brake pad (brake element)

7A

electric motor (motor, electric mechanism),

8th

rotary-linear motion conversion mechanism (electrical mechanism),

24

Parking brake control device (control device, electric brake control device)

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• JP 2013209041A [0003]
• JP 6017162 B2 [0003]
• JP 2020062317 [0097]

Claims (7)

An electric braking device comprising: a motor configured to drive an electric mechanism configured to hold a braking force by pressing a braking element against a braked element; and a controller configured to control driving of the motor, wherein the controller is configured to energize the motor upon releasing the holding of the braking force and to change a driving time of the motor in accordance with a current change amount at a predetermined interval after a predetermined time has elapsed since a current value of the motor starts decreasing after rising, and a current value at which the current change amount of the motor converges to a predetermined value or less. The electric braking device after claim 1 , wherein the predetermined interval changes in accordance with a variation width of the current value depending on a temperature of the motor. The electric braking device after claim 1 or 2 , wherein the current value at which the current change amount of the motor converges to the predetermined value or less is detected from a current waveform obtained through a differential filter. An electric braking device comprising: a motor configured to drive an electric mechanism configured to hold a braking force by pressing a braking element against a braked element; and a controller configured to control driving of the motor, wherein the controller is configured to energize the motor upon releasing the holding of the braking force and to change a driving time of the motor based on a current value generated in every predetermined cycle is detected after the current value of the motor increases and then decreases to enter a predetermined current value range, and a current value at which the current value becomes substantially constant. The electric braking device after claim 4 , wherein the predetermined current value range changes in accordance with a variation width of the current value depending on a temperature of the motor. The electric braking device after claim 4 or 5 , wherein the current value at which the current value becomes substantially constant is a current value at which a change in a derivative value of the current value obtained by a differential filter becomes equal to or smaller than a predetermined value. An electric brake control device for controlling a motor configured to drive an electric mechanism configured to hold a braking force by pressing a braking element against a braked element, the electric brake control device is configured, upon releasing the holding of the braking force, to energize the motor and change a driving time of the motor in accordance with an amount of current change at a predetermined interval after a predetermined time has elapsed since a current value of the motor after an increase starts to decrease, and a current value at which the current change amount of the motor converges to a predetermined value or less.

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